Bolt lock



Uec. 3', 1935n J, STAEMPFL; 2,022,946

BOLT LocK Filed Jan. l0, 1955 wir Patented Dec. 3, 1935 UNITED STATESPATENT OFFICE 2 Claims.

The present invention relates to improvements in bolt locks, and has foran object to provide an improved construction of bolt lock which willeifectually prevent the bolt from turning or being backed olf from thelocking device.

Another object of the invention is to provide an improved device of thiskind in which such protection is aiforded the locking device that accessthereto cannot be had for the purpose of shearing olf parts with a viewto releasing the bolt.

A further object of the invention is to provide a device of this kindwhich will simulate a nut and will thus give rise to the impression thatmethods similar to the release of locked nuts may be resorted to, butwhich methods will be ineffectual to dislodge the improved device.

The invention is applicable to brake tags, license plate holders, and tomany other uses where non-removable bolts are desired.

With the foregoing a-nd other objects in View, the invention will bemore fully described hereinafter, and will be more particularly pointedout in the claims appended hereto.

In the drawing, wherein like symbols refer to like or correspondingparts throughout the several views;

Figure 1 is a sectional view taken through a casing shown held in placeby the improved bolt lock.

Figure 2 is a longitudinal section, taken on an enlarged scale, throughthe bolt and its locking device with the bolt in an initial position.

Figure 3 is a similar view showing the bolt as driven home.

Figure 4 is a cross section taken on the line 4 4 in Figure 2.

Figure 5 is an end view of the locking device.

Figure 6 is a cross section taken on the line 6 6 in Figure 3.

Figure 7 is a perspective View, shown partly in section and partlybroken away, of the casing for the locking spring, and

Figure 8 is a cross sectional view taken on the line 8 8 in Figure 2.

Referring more particularly to the drawing, IU designates the threadedshank of a bolt having a head I I with a cross cut I 2, or other shapedhead construction to receive a screw driver or Wrench or other implementby which the bolt or the screw may be rotated to cause it to assume afastening position.

The bolt is adapted to be screwed into a coil spring I3 contained withina casing I4. The casing itself is entirely devoid of threads and is madewith a plain cylindrical wall I5, as shown in Figure 7, so that the coilspring I3 may turn freely within the casing I4, as hereinafterexplained. Interiorly there projects into the cavity of the casing anannular shoulder I6, such shoulder 5 being at the inner end of thecasing and acting as an abutment for one end of the coil spring I3. Thiscoil spring I3 is assembled with the casing I4 by sliding the sameaxially through the outer end of the casing I 4 until the inner end ofthe 10 spring strikes the abutment shoulder I6. In order to allow of theintroduction of the coil sp-ring I3 within the casing I4, the forwardends thereof will be originally produced in an expanded position. Afterthe spring has been introduced, the 15 end portions I'I of the casing I4are hammered or pressed inwardly in a radial direction, which ispermitted by the slot formation I8, thus pre-` venting the escape of thecoil spring I4 outwardly, but leaving an opening for the passage of the20 bolt II). The slotted construction I8 also forms a projectioninterior of the casing I4 adjacent the outer terminal end I9 of the coilspring I3.

The casing I4 is provided with a hexagonal or other nut portion 2!!which may take a Wrench 25 or other tool to hold the casing I4 againstturning.

The convolutions oi the coil spring I3 are preferably of substantiallythe same pitch as the pitch of the screw threaded shank of the bolt 30whereby these threads will substantially mate.

In the use of the device, the bolt I0 is first introduced into thecasing I4, as indicated in Figure 2, the threads of the bolt I Il beingrotated into convolutions 0f the spring I3. When the 35 bolt is screwedinto the casing and into the coil spring, such coil spring I3 forms ineifect a ratchet. There will be a tendency of the bolt I0 to carry thecoil spring I3 around with it due to friction between the threads of thebolt and 40 the convolutions of the spring, but the leading end I9 ofthe coil spring, as shown in Figure 8, will catch upon a projection,such for instance as one of the edges of a slot I8, and hold the coilspring while the bolt is rotated therethrough for 45 instance to theposition shown in Figure 3, which position we will assume is necessaryto secure a close approach of the bolt head II and the adjacent end ofthe casing I4, whereby to clamp therebetween the base wall 2l of acasing such 50 as shown in Figure 1.

This may be a pressed metal cap or casing 22 having a glass or Celluloidcover 23. The construction is such as is usually encountered in braketags, or license plate holders, etc. 55

Whenever an attempt is made to unscrew the bolt I0, the coil spring I3will turn with the bolt which prevents it from being loosened regardlessof the amount of pressure, friction or vibration which might be placedon the so-called nut or casing I4. In screwing the bolt I0 through thecoil spring in the rst instance, the movement is a clockwise movement aslooked at in Figure 8. The leading edge I9 of the coil spring will movein the direction of the arrow A causing it to catch in a projection andarrest movement of the coil spring and permit threading of the bolt I0into such coil spring I3. However, when attempt is made to back off thebolt IIJ, the motion'will be in the direction of arrow B, which causesthe end of the coil spring I9 to be a trailing end which cannot catch inprojection and thereby the coil spring I3 will turn around looselywithin the casing I4 and the bolt will not be turned out of theconvolutions of the coil spring I3. The bolt together with the coilspring I3 and its casing I4 form a locked combination effectuallypreventing the separation of the parts with or without a wrench unlessthe casing is completely destroyed by cutting it entirely 01T.

Even if the bolt is tightened to the point where the threads arestripped, the bolt cannot be removed. The coil spring I3 is entirelyenclosed which makes it impossible to remove same by cutting the end ofthe spring or by shearing the spring off. Neither end of the coil springI3 is exposed.

It is obvious that various changes and modiiications may be made in thedetails oi construction and design of the above specically describedembodiment of this invention without departing from the spirit thereof,such changes and modications being restricted only by the scope of thefollowing claims:

What is claimed is:-

1. The combination with a threaded bolt of a casing having a plaininternal cylindrical wall of substantially greater diameter than thediameter of the bolt and adapted to embrace at least a portion of suchbolt, said casing having at its inner end an abutment projectinginwardly of said plain Wall, the outer portion of the casing beingslotted, a coil spring contained floatingly within said casing andlimited in one direction of axial movement by said abutment, said coilspring having a pitch to mate with the threads on the bolt, the outerslotted portion of said casing projecting inwardly of the said plainwall and having a projection in the path of the adjacent end of thespring whereby when the spring is turned in one direction so that itsend becomes leading such leading end will engage the projection and holdthe coil spring against movement while the bolt is screwed therein.

2. The combination with a threaded bolt, of a casing having a plaininternal cylindrical wall of substantially greater diameter than thediameter of the bolt and adapted to embrace at least a portion of suchbolt, said casing having at its inner and outer end portions abutments,a coil spring within the casing confined at its ends against substantialaxial movement by said abutments and having a pitch substantially matingwith the threads of the bolt, whereby the bolt may be screwed into thecoil spring, said casing having a projection therein projecting into thepath of rotation of one end portion of the coil o

